1. Field of the Invention
The present invention relates to an imaging apparatus which detects flicker based on brightness changes in captured images, and a corresponding flicker detection method and program stored in a non-transitory computer-readable storage medium.
2. Description of the Related Art
When an imaging apparatus such as a digital video camera captures images under an environment with a light source (for example, fluorescent tube) where brightness is periodically changed in accordance with a commercial power supply frequency (for example, 50 Hz or 60 Hz), the brightness of the light source changes with a period of 1/100 seconds in a case where the commercial power supply frequency is 50 Hz or a period of 1/120 seconds in a case where the commercial power supply frequency is 60 Hz, which may cause light and dark stripes in image signals. In this case, in an image sensor (CMOS: Complementary Metal-Oxide Semiconductor) of a rolling shutter type (line exposure sequential reading type), imaging for one frame is performed while exposure timing is shifted for each line. Therefore, a striped pattern may appear in a vertical direction on captured images, which causes flicker.
As a technique for detecting this flicker, a technique is conventionally known in which, when the presence or absence of a flicker occurrence factor such as a fluorescent lamp is to be detected in an imaging apparatus including an image sensor of a rolling shutter type, the occurrence status of stripes in captured images is analyzed to detect a frequency of flicker components of the fluorescent light (refer to Japanese Patent Application Laid-Open (Kokai) Publication No. 2004-007402).